This invention relates to surfactant compositions useful in enhanced oil recovery processes. In one aspect, the invention relates to surfactant compositions comprising a glycol ether while in another aspect, the invention relates to the use of the surfactant compositions in an aqueous flooding process for removing oil from a porous, subterranean rock reservoir.
Chiu et al., U.S. Pat. No. 3,945,437, teach multicomponent aqueous anionic surfactant systems consisting of an aromatic ether polysulfonate, a petroleum sulfonate, and alkoxy alcohol sulfates. The interfacial tension between these systems and oil is less than about 0.1 dyne per centimeter and the systems are taught to have good tolerance toward salts of mono- and/or multivalent cations found in the brine of many oil reservoirs. While these surfactant systems have demonstrated utility in the removal of oil from a porous, subterranean rock reservoir, their use toward this end is not without cost.
A significant factor in the cost of using aqueous anionic surfactant systems for the displacement of oil from a subterranean rock reservoir is loss of the surfactant system to the rock reservoir by adsorption, i.e., attachment of the active surfactant components to the reservoir surface. The extent of surfactant adsorption is primarily dependent upon the physical and chemical properties of the reservoir but given the relatively high cost of the surfactant systems, any decrease in the loss due to adsorption can be an economically significant factor in the production of oil from the reservoir.